list3=["张三","李四","王五","马六","吴七"]
s=input("请输入一个姓名")
a=0
for i in list3:
    if(i==s):
        print("存在下标"+i+"，下标为：",end="")
        print(list3.index(i))
        break
    else:
        print('不存在')